This invention relates to a fuel supply system for a gas-fueled engine and more particularly to an improved charge forming system for a gas-fueled engine.
It has been proposed to operate internal combustion engines on a gaseous type of fuel which is stored under high pressure as a liquid (L.P.G.). The gaseous fuel is then delivered to the engine through some form of charge forming system after the pressure of the gaseous fuel has been regulated to a pressure that is at or slightly above atmospheric pressure. The use of this type of fuel has a number of advantages, particularly due to its clean burning nature. This not only prolongs engine life and can reduce service intervals, but also offers prospects of increased exhaust emission control, fuel economy and conservation of fuel reserves.
Although such gaseous fuels have the aforenoted advantages, it is somewhat more difficult to control accurately the air/fuel ratio with gaseous fuels because of their nature. For example, it has been proposed to control the air/fuel ratio of a gaseous fueled engine by mixing atmospheric air with the gaseous fuel before the fuel is delivered to the charge former. However, this has previously been done by mixing the atmospheric air with the gaseous fuel after the fuel has been passed through a flow regulating throttle type valve. As a result, the air is mixed with the fuel when it is at an extremely low absolute pressure and which may, in fact, even be slightly less than atmospheric pressure. As a result, when the air is added, the amount of gaseous fuel supplied is not reduced and the air/fuel ratio cannot be as accurately controlled as desired.
It is, therefore, a principal object to this invention to provide an improved charge forming system for an engine operated on a gaseous fuel.
It is a further object to this invention to provide a charge forming system for a gaseous fueled engine wherein the air/fuel ratio can be accurately controlled.
It is a further object to this invention to provide a charge forming system for a gaseous fueled internal combustion engine wherein the air/fuel ratio is controlled by mixing air with the gaseous fuel after the pressure of the gaseous fuel has been regulated but before the flow of the gaseous fuel is throttled in the charge forming device.